Results and Discussion
Synthesis and Thermal Properties
In order to obtain the key intermediates 2a–2c , we used the Knoevenagel condensation reaction method reported in the literature.[19 ] The intermediate compound 3 was prepared by using lithium diisopropylamide (LDA) and pinacol borate according
to the literature.[12 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ]
[18 ] Finally, the key intermediates 2a–2c were respectively coupled with compound 3 using the Suzuki coupling method with the catalyst Pd(PPh3 )4 to prepare the three target conjugated compounds DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT.
The synthetic routes of the target conjugated compounds and intermediates are shown
in [Scheme 1 ]. The final products were structurally confirmed by nuclear magnetic resonance (NMR)
and high-resolution mass spectrometry (HRMS). At the same time, in order to ensure
the feasibility of annealing in subsequent OFET device processing to optimize charge
carrier transport performance, the good thermal stability of these compounds is necessary.
It is considered that thermogravimetric analysis (TGA) can usually be used to detect
the thermal properties of organic semiconductor materials.[20 ] We performed the TGA of these conjugated compounds to detect their thermal properties.
The TGA results of these conjugated compounds are shown in [Figure S1 ] and the corresponding data are listed in [Table 1 ]. According to the TGA data, the three conjugated compounds DPP-BVCNT, DPP-2FBVCNT,
and DPP-3FBVCNT showed their 5% weight loss at 401.6, 407.3, and 409.6 °C, respectively.
These temperature data indicated that the degradation temperatures of these three
conjugated organic small-molecule compounds were all above 400 °C, and thus these
organic compounds showed good thermal stability. This provides a good stability guarantee
for the optimization of annealing in the preparation of corresponding OFET devices.
Scheme 1 Synthetic routes of DPP-BVCNT–based compounds.
Table 1
Thermal, optical, and electrochemical properties of small molecules based on DPP-DBVCNT
Compd
T
d
[a ] (° C)
λ
max
[b ] (solution) (nm)
λ
max
[b ] (film) (nm)
E
g (opt)[c ] (eV)
E
HOMO
(eV)
E
LUMO (eV)
E
g(ec)
d
(eV)
DPP-BVCNT
401.6
595
711
1.58
−5.51
−3.67
1.84
DPP-2FBVCNT
407.3
596
713
1.59
−5.68
−3.69
1.99
DPP-3FBVCNT
409.6
595
694
1.60
−5.67
−3.67
2.00
a Temperature at 5% weight loss.
b Maximum absorption wavelengths in chloroform solution and film state.
c Calculated according to the wavelength at the peak onset in the UV-Vis-NIR absorption
spectra in the film state.
d Estimated from the HOMO and LUMO energy levels.
Optical Properties
The photophysical properties of the three DPP-DBVCNT–based conjugated compounds DPP-BVCNT,
DPP-2FBVCNT, and DPP-3FBVCNT were measured by using UV-Vis-NIR spectroscopy. The UV-Vis-NIR
absorption spectra of these three compounds in chloroform solutions (concentration
10−5 M) and thin films are shown in [Figures 1 ] and [S2 ].
Figure 1 UV-Vis-NIR absorption spectra of small-molecule compounds (a ) DPP-BVCNT, (b ) DPP-2FBVCNT, and (c ) DPP-3FBVCNT in chloroform solutions and thin films.
From the UV–Vis–NIR absorption spectra, we found that in the chloroform solutions
([Figure S2a ]), the maximum absorption wavelengths of DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT
were 595, 596, and 595 nm, respectively, with almost no significant difference. In
the films ([Figure S2b ]), the maximum absorption wavelengths of DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT
were 711, 713, and 694 nm, respectively, also without significant difference. However,
by comparing the absorption in solution and films of each material (as shown in [Figure 1a–c ]), we found two differences. One difference was that the corresponding absorption
peak of the maximum absorption wavelength in solution was found to be close to the
Gaussian distribution, while in films it exhibited obvious shoulder peaks showing
a clear aggregation effect. The other difference was that the maximum absorption wavelength
of the thin film showed a red-shift of about 100 nm (99–117 nm) compared to that of
the respective solution. It can be seen that the aggregation effect of each organic
small-molecule material in the film is much higher than that in the corresponding
solution. It can be also reflected from the side angle that there was a high degree
of dispersion for this series of materials in the chloroform solution. And there was
almost no preaggregation phenomenon for these three materials in solution, which should
be beneficial for the processing of corresponding OFET devices by the solution method.
The peak shapes of the absorption peaks at the maximum absorption wavelengths of the
three materials were almost identical for each both in the solution and film state.
To a certain extent, it was reflected that the dispersion of these three materials
in chloroform solution and the degree of aggregation after film forming were almost
the same.
The peak onsets of the UV-Vis-NIR absorption spectra (λ
onset ) of these small-molecule compounds' films were used to calculate the optical band
gap Eg
(opt) according to the formula Eg
(opt) = 1,240/λ
onset . The absorption peaks' onsets of DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT were 786,
779, and 776 nm, respectively. These onset values were put into the above formula
to obtain the optical band gaps of the small-molecule compounds as 1.58, 1.59, and
1.60 eV (see [Table 1 ]), almost without any significant difference. The above results indicated that for
these conjugated compounds, the aggregation-effect difference between in chloroform
solution and in film was significant. But both the F-substitution and its position
on the donor units of the conjugated backbone had little effect on the absorption
spectra and the optical band gaps.
Electrochemical Properties
We used cyclic voltammetry (CV) to study the electrochemical performance of the three
conjugated compounds. In the CV test, silver/silver chloride (Ag/AgCl) was used as
a reference electrode, trace ferrocene as an internal standard, and a Pt electrode
coated with an organic thin film as a working electrode. All measurement data were
collected at room temperature under an argon atmosphere. The HOMO and LUMO energy
levels of the small-molecule compounds were estimated by using the equations E
HOMO = –(E
ox
onset – E
Fc
+ 4.80) eV and E
LUMO = –(E
re
onset – E
FC + 4.80) eV at the starting point of the respective oxidation peaks and reduction
peaks. As shown in [Figure 2 ], the initial oxidation/reduction potentials of DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT
were located at 1.11/−0.73, 1.28/−0.71, and 1.27/−0.73 eV, respectively. Based on
these initial potential values and then calculated according to the above equations,
the HOMO/LUMO energy levels of DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT were obtained
as −5.51/−3.67, −5.68/−3.69, and −5.67/−3.67 eV ([Table 1 ]), respectively. These observations indicated that the introduction of the F atoms
on the donor moieties of the D–A type conjugated backbone could significantly lower
the HOMO energy level of these small-molecule compounds. In addition, from the above
oxidation/reduction potential data, we estimated the HOMO–LUMO band gaps E
g = (E
ox
onset – E
re
onset )[21 ] of DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT to be 1.84, 1.99, and 2.00 eV, respectively
([Figure 2 ] and [Table 1 ]). Among them, the F-substituted conjugated compounds DPP-2FBVCNT and DPP-3FBVCNT
showed no significant difference in HOMO–LUMO band gaps E
g for each other, but both showed a 0.15–0.16 eV wider band gap compared to that of
DPP-BVCNT without the F atoms. It could be seen that the introduction of the F atoms
widened the HOMO–LUMO band gap E
g of these conjugated compounds obviously.
Figure 2 Cyclic voltammetry curves of DPP-DBVCNT–based compounds in an acetonitrile solution
containing 0.1 M electrolyte n-Bu4 NPF6 and trace ferrocene as internal standard.
From the above observations and calculations of these compounds, the introduction
of the F atoms exhibited an important influence on their electronic structures. It
is beneficial to lower the HOMO energy levels and facilitate the HOMO–LUMO band gaps
to be widened. The differences between the optical band gaps and the electrochemical
band gaps of these compounds are 0.26–0.40 eV within the acceptable experimental error
range according to the literature.[22 ]
Charge Carrier Transport Performance
To ensure that the relevant n-type or ambipolar field-effect performance of organic
conjugated small molecules based on DPP-DBVCNT is reflected as accurately as possible,
we used the TGBC structure with poly(methyl methacrylate) as the dielectric layer
to prepare the OFET devices. These devices were used to study the charge carrier transport
performance of the three conjugated compounds DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT.
The TGBC structure can effectively reduce the negative effects of moisture and oxygen,
thereby enhancing the ambipolar or n-type charge transport of organic semiconductors.[23 ]
[24 ] As the devices' performance is largely affected by the thermal annealing process,
the films of these compounds were also thermally annealed. Considering that different
materials generally need be annealed at different temperatures to achieve their own
highest performances, we call the highest performance-related annealing temperatures
as the optimum annealing temperatures. In order to get the optimum annealing temperatures,
the performances of the corresponding OFETs of each material film were investigated
after being annealed at different temperatures in the range of 120–240 °C. The study
found that DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT exhibited different degrees of
p-type or ambipolar performances and their optimum annealing temperatures were 240,
170, and 140 °C, respectively.
According to the above optimal annealing temperatures, TGBC configurational OFET devices
based on the above three organic materials were prepared and the corresponding charge
carrier transport performance was detected in air. The OFET devices based on DPP-BVCNT
showed a certain degree of p-type OFET performance, while both the DPP-2FBVCNT– and
DPP-3FBVCNT–based OFET devices showed obvious ambipolar field-effect performances.
Typical transfer and output curves for the OFET devices based on these three small-molecule
compounds are shown in [Figure 3 ]. All the corresponding parameters are shown in [Table 2 ]. According to the listed saturation mobility values of the small-molecule compound-based
OFET devices, the p-type material DPP-BVCNT showed the highest hole mobility (μ
hmax ) of 1.57 × 10−3 cm2 V−1 s−1 . The highest hole/electron mobility (μ
hmax /μ
emax ) values of the two ambipolar compounds DPP-2FBVCNT and DPP-3FBVCNT were 0.0231/0.220
and 0.0351/0.0196 cm2 V−1 s−1 , respectively. The two ambipolar materials DPP-2FBVCNT and DPP-3FBVCNT exhibited
similar hole mobilities but largely different electron mobilities. DPP-2FBVCNT exhibited
almost an order of magnitude higher electron mobility than that of the DPP-3FBVCNT
with one F atom substituted on each of the two inner sides (μ
emax : 0.220 vs. 0.0196 cm2 V−1 S−1 ). DPP-2FBVCNT had one F atom substituted on each of the two outer sides of the compound,
which were on 2-positions of the benzene rings of the two BCNVT donor units and relatively
far away from the DPP acceptor unit.
Figure 3 Typical transfer and output curves of OFETs based on the compounds DPP-BVCNT (a–b ), DPP-2FBVCNT (c–f ), and DPP-3FBVCNT (g–j ).
Table 2
The performances and relative crystalline parameters of the OFET devices with top-gate-bottom-contact
(TGBC) configurations
Compd
µ
hmax (cm2 V−1 s−1 )
I
ON /I
OFF
V
th (V)
µ
emax (cm2 V−1 s−1 )
I
ON /I
OFF
V
th (V)
d –d
[a ](Å)
π -π
[a ] (Å)
DPP-BVCNT
1.57 × 10−3
104
−11.69
–
–—
–
24.5
3.71
DPP-2FBVCNT
2.31 × 10−2
106
−48.05
2.20 × 10−1
107
82.48
24.3
3.69
DPP-3FBVCNT
3.51 × 10−2
104 –105
−48.62
1.96 × 10−2
103
48.81
23.7
3.55
a Stacking distance was calculated from each of the annealed organic films.
Among these three compounds, the DPP-BVCNTVT–based OFET devices exhibited the lowest
on/off current ratios (I
on /I
off ) of ∼104 and the highest threshold voltage (V
th ) of –11.69. This might be presumably due to some unintentional doping effects and
charge trapping at the compound/oxide and/or the grain boundary interfaces according
to the literature reported.[25 ] The DPP-3FBVCNT–based devices showed almost similar threshold voltages to those
of DPP-2FBVCNT–based devices, maybe because of their nearly similar HOMO/LUMO energy
levels, which might be due to the similar conformational lock effects from the F…H
bonds in the two compounds according to previous research performed by our group.[26 ]
[27 ]
From the above results, it can be seen that in these DPP-DBVCNT–based organic conjugated
small molecules, the substitution and the position of the F atoms introduced into
the benzene rings of the donor units had significant effects on the charge carrier
transport. It is interesting to note that the introduction of one F atom into each
of the donor benzene rings on both sides of the DPP acceptor unit was beneficial to
make the performance of the DPP-BVCNT–based compound be changed from p-type to ambipolar.
The compound with one F atom substituted on each of the outer sides showed a higher
electron mobility compared to that of the inner side-substituted one. Meanwhile, the
compound with one F atom substituted on the inner sides exhibited a better balance
of ambipolar performances than that of the outer side-substituted one.
Characterization of Thin-Film Microstructure
The surface morphology and intermolecular aggregation of these three conjugated compounds
were mainly analyzed using the height maps obtained via atomic force microscopy (AFM)
scanning and the diffraction patterns obtained by a two-dimensional grazing incidence
X-ray diffraction (2D-GIXRD) test ([Figure 4 ]). In regard to the surface microscopic morphology of the organic films, we used
the tapping mode AFM to scan the films, and the detection results are shown in [Figure 4a–c ]. The AFM height maps of the DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT thin films were
collected after annealing at their respective optimum annealing temperatures. The
DPP-2FBVCNT thin film exhibited the largest crystal grains and good continuity among
these three thin films. This morphology was more favorable for charge carrier transport,
which was consistent with the fact that its ambipolar field-effect performance was
the best among these three materials. Moreover, the DPP-3FBVCNT thin film also showed
a certain continuous surface morphology, thus it also exhibited a certain ambipolar
field effect.
Figure 4 AFM height images (a –c ) and 2D-GIXRD diffraction patterns (d –f ) of the DPP-BVCNT (a, d ), DPP-2FBVCNT (b, e ), and DPP-3FBVCNT (c, f ) thin films after thermal annealing treatment. AFM images are 2 μm × 2 μm in size.
In order to further understand the relationship between OFET performances and molecular
structures, their films were subjected to 2D-GIXRD tests after annealing at their
respective optimum annealing temperatures. The obtained 2D-GIXRD results are shown
in [Figure 4d–f ]. The out-of-plane (q
z ) orientation (100) Bragg peaks of 24.5, 24.3, and 23.7 Å correspond to the d –d spacing distances of the compounds DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT, respectively.
In the in-plane (q
xy ) orientation, the π–π stacking distances of the three compounds' (010) Bragg in-plane
peaks are 3.71, 3.69, and 3.55 Å for the DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT thin
films, respectively. All of the above relevant parameters are listed in [Table 2 ]. The in-plane (q
xy ) and out-of-plane (q
z ) direction (010) Bragg peaks provided by the 2D-GIXRD diffraction patterns showed
that these thin films exhibited a molecular packing pattern of edge-on and face-on
mixed orientations relative to the substrates. Interestingly, among these 2D-GIXRD
diffraction patterns, DPP-2FBVCNT showed the strongest out-of-plane (q
z )-oriented (h00) diffraction (100) and (200) Bragg peaks, even the obvious (010) Bragg
in-plane peak could be directly observed ([Figure 4e ]). This indicates that the DPP-2FBVCN film had the best crystallinity and best orderly
layered structure which was consistent with the best field-effect performance among
the three small molecules. The 2D-GIXRD patterns corresponding to the other two materials
DPP-BVCNT and DPP-3FBVCNT ([Figure 4d, f ]) showed relatively weak intensities of the diffraction peaks, which were also consistent
with their relatively low field-effect performances.
The above 2D-GIXRD and AFM results ([Figure 4 ]) for DPP-BVCNT, DPP-2FBVCNT, and DPP-3FBVCNT were combined with the aforementioned
optical absorption spectra, electrochemical performance data ([Figures 1 ] and [2 ], [S2 ], and [Table 1 ]), and charge carrier transport performance data ([Table 2 ] and [Figure 3 ]), and an analysis of the data was performed. The combined consideration and analysis
results showed that the F-substitution and its position on the donor BCNVT units had
a significant influence on their electronic structures, the surface morphology of
the thin films, the molecular packing mode, and charge carrier mobilities. In other
words, the F-substitution and its position on the donor units of the conjugated backbones
played an important role in regulating the molecular electronic structure, the accumulation
between the conjugated frameworks and the intermolecular interaction, and thus to
some extent in affecting the microstructures of the compound films and charge carrier
transport performances. The introduction of the electron-withdrawing F atoms had no
obvious influence on the absorption spectroscopy of these small-molecule materials.
But to a certain extent, it was beneficial to lower the HOMO energy levels, broaden
the HOMO–LUMO energy gaps, improve the molecular aggregation, and remarkably change
the performance from p-type to ambipolar especially for the outer side F-substituted
compound DPP-2FBVCNT.
Experimental Section
Reagents and Reactions
All chemicals used in this work were purchased from Innochem, Acros, Alfa Aesar, J&K
Scientific, Sigma-Aldrich, etc. The chemicals were in general used without further
purification unless otherwise specified. If necessary, toluene and tetrahydrofuran
(THF) were freshly distilled using sodium as a water scavenger and using benzophenone
as an indicator according to the standard procedures. All Suzuki coupling reactions
were operated under the protection of the argon atmosphere in Schlenk reactors.
Measurements and Characterization of Compounds
1 H NMR, 13 C NMR, and 19 F NMR spectra of synthetic intermediates and target small molecules were tested and
recorded on a Bruker Avance III 400 HD NMR spectrometer or were characterized by using
a Bruker Avance III 500WB NMR spectrometer. The reported 13 C NMR spectra were not 19F decoupled and hence were reported as empiric enumeration
of the observed signals. HRMS measurements of all compounds related were collected
on a 9.4T Solarix FT-ICR mass spectrometer or an APEX II FT-ICR mass spectrometer.
TGA measurement data of target small molecules were collected by a PerkinElmer Pyris
series TGA8000 thermal analysis system. The UV–Vis–NIR absorption spectra of all synthesized
DPP-BVCNT–based small molecules were recorded by using a Hitachi U-3010 spectrophotometer.
The CV data obtained on a conventional three-electrode type electrochemistry workstation
were used to characterize the electrochemical properties. The three electrodes were
respectively as follows: a Ag/AgCl electrode as the reference electrode, a platinum
wire as the counter electrode, a glassy carbon stick electrode coated with a DPP-BVCNT–based
small-molecule thin film layer as the working electrode. A 0.1 M anhydrous solution
of tetrabutylammonium hexafluorophosphate in acetonitrile saturated with argon was
adopted as the supporting electrolyte. The corresponding oxidative and reductive peaks'
onsets of the small molecules were used to estimate the HOMO and LUMO energy levels
with the equations: E
HOMO = –(E
ox
onset + 4.4) eV and E
LUMO = –(E
re
onset + 4.4) eV. Thin-film morphologies were analyzed by using a tapping mode Digital Instruments
Nanoscope V atomic force microscope. The data of GIXRD were obtained by illuminating
the thin-film samples at 0.2°. All the samples used in the tests of AFM, 2D-GIXRD,
and OFET performance analysis were same.
Synthetic Procedure
The synthetic routes of the conjugated small molecules DPP-BVCNT, DPP-2FBVCNT, and
DPP-3FBVCNT are shown in [Scheme 1 ]. Intermediate compounds 2a–2c and 3 were prepared according to the reported methods.[12 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ]
[18 ]
[19 ]
General Preparation Method of the Key BVCNT-Based Intermediates (2a–2c)
The intermediates were prepared according to the method reported in literature.[19 ] Potassium tert -butoxide (25.0 mmol) was added to anhydrous methanol (50 mL) and stirred until completely
dissolved. After the mixture was cooled to room temperature, 2-(thiophen-2-yl)acetonitrile
(25.0 mmol) was added into it, followed by 1 hour of stirring, then one of the compounds
1a –1c (25.0 mmol) was added and the mixture was stirred overnight. The precipitate was
filtered to get the filter cake which was further purified by recrystallization from
methanol to obtain the corresponding intermediate (2a –2c ) as a yellow or white powder (yield: 28–84%).
4-BrBVCNT (2a): (white powder, yield: 84%). 1 H NMR (400 MHz, CDCl3 , TMS): δ = 7.71–7.68 (m, 2H), 7.58–7.54 (m, 2H), 7.39–7.38 (m, 1H), 7.33–7.31 (m, 1H), 7.28
(s, 1H), 7.08–7.05 (m, 1H). 13 C NMR (101 MHz, CDCl3 , TMS): δ = 138.89, 137.99, 132.27, 132.27, 132.27, 130.46, 130.46, 128.25, 127.67, 126.65,
124.83, 116.61, 106.80. HRMS (MALDI): calcd. for C13 H9 BrNS [M + H]+ (289.9639); found: 289.9636. HRMS (MALDI): calcd. for C13 H8 BrNNaS [M + Na]+ (311.9453); found: 311.9456.
2-F-4-BrBVCNT (2b): (yellow powder, yield: 56%). 1 H NMR (400 MHz, CDCl3 , TMS): δ = 8.09 (t, J = 8.0 Hz, 1H), 7.49 (s, 1H), 7.42–7.38 (m, 2H), 7.36–7.31 (m, 2H), 7.09–7.07 (m,
1H). 13 C NMR (101 MHz, CDCl3 , TMS): δ = 161.62, 159.06, 138.71, 129.39, 129.01, 128.24, 128.15, 128.11, 128.08, 127.21,
119.68, 116.28, 108.59. 19 F NMR (470 MHz, CDCl3 , TMS): δ = −111.88. HRMS (MALDI): calcd. for C13 H8 BrFNS [M + H]+ (307.9539); found: 307.9541.
3-F-4-BrBVCNT (2c): (yellow powder, yield: 28%). 1 H NMR (400 MHz, CDCl3 , TMS): δ = 7.65–7.60 (m, 2H), 7.51–7.48 (m, 1H), 7.42–7.41 (m, 1H), 7.36–7.34 (m, 1H), 7.26
(s, 1H), 7.10–7.07 (m, 1H). 13 C NMR (101 MHz, CDCl3 , TMS): δ = 160.83, 157.54, 138.50, 136.52, 134.44, 134.11, 128.34, 128.18, 127.09, 125.86,
116.24, 111.53, 108.00. 19 F NMR (470 MHz, CDCl3 , TMS): δ = −105.58. HRMS (MALDI): calcd. for C13 H8 BrFNS [M + H]+ (307.9539); found: 307.9541.
General Preparation Procedure of DPP-BVCNT–Based Compounds
One of the BVCNT-based key intermediates 2a –2c (0.60 mmol), bisborate-DPP (3 ) (0.25 mmol), 2 M aqueous Na2 CO3 solution (6 mL), and toluene (20 mL) were successively added to a 50 mL Schlenk flask.
After the flask was strictly charged with Ar, Pd(PPh3 )4 (0.06 mmol) and KF (0.3 mmol) were added quickly. Then the above mixture under an
Ar atmosphere was heated to 110 °C and stirred at this temperature for 48 hours. The
reaction mixture was cooled to room temperature and the catalyst was removed by filtration
through a short silica gel pad with the eluent ethyl acetate (EA). After washing with
water and brine and then dried with Na2 SO4 , the combined EA filtrate was concentrated in vacuo . Silica gel chromatography was adopted to purify the above residue with the eluent
dichloromethane/petroleum ether and squatting from chloroform/methanol resulted in
the target compound as a dark green or blue-black or brown viscous solid.
DPP-BVCNT (yield: 48%). 1 H NMR (500 MHz, 373.2 K, CDCl2 CDCl2 , TMS): δ = 8.84 (d, J = 4.1 Hz, 2H), 7.91 (d, J = 8.3 Hz, 4H), 7.77 (d, J = 8.3 Hz, 4H), 7.55 (d, J = 4.1 Hz, 2H), 7.43 (d, J = 3.5 Hz, 2H), 7.40–7.31 (m, 4H), 7.16–7.05 (m, 2H), 4.07 (d, J = 7.6 Hz, 4H), 2.02 (s, 2H), 1.39–1.23 (m, 80H), 0.92–0.84 (m, 12H, -CH3 ). 13 C NMR (126 MHz, 373.2 K, CDCl2 CDCl2 , TMS): δ = 161.72, 148.20, 139.88, 139.29, 138.39, 136.31, 135.13, 133.83, 130.13, 129.90,
128.23, 127.42, 126.72, 126.50, 125.42, 116.67, 109.23, 106.80, 46.75, 38.12, 31.83,
30.01, 29.62, 29.58, 29.51, 29.24, 26.58, 22.56, 13.93. HRMS (MALDI): calcd. for C88 H119 N4 O2 S4 [M + H]+ (1391.8210); found: 1391.8199. Elemental anal. calcd. for C88 H118 N4 O2 S4 : C 75.92, H 8.54, N 4.02. Found: C 77.45, H 8.41, N 4.20.
DPP-2FBVCNT (yield: 56%): 1 H NMR (500 MHz, 373.2 K, CDCl2 CDCl2 , TMS): δ = 8.72 (d, J = 4.0 Hz, 2H), 8.19 (t, J = 8.0 Hz, 2H), 7.50 (d, J = 10.0 Hz, 4H), 7.44 (d, J = 4.0 Hz, 2H), 7.36 (t, J = 3.5 Hz, 4H), 7.28 (d, J = 5.0 Hz, 2H), 7.01 (t, J = 4.0 Hz, 2H), 3.97 (d, J = 7.5 Hz, 4H), 1.91 (m, 2H), 1.32–1.16 (m, 80H), 0.79–0.77 (m, 12H, -CH3 ). 13 C NMR (126 MHz, 373.2 K, CDCl2 CDCl2 , TMS): δ = 162.12, 161.63, 160.10, 146.79, 139.79, 139.14, 137.07, 137.01, 136.29, 130.64,
129.78, 128.98, 128.27, 127.83, 127.26, 125.97, 122.18, 116.37, 113.02, 112.83, 109.44,
108.48, 46.75, 38.14, 31.85, 31.82, 30.01, 29.58, 29.55, 29.51, 29.23, 26.58, 22.56,
13.93. 19 F NMR (470 MHz, 373.2 K, CDCl2 CDCl2 , TMS): δ = −132.74. HRMS (MALDI): calcd. for C88 H117 F2 N4 O2 S4 [M + H]+ (1427.8022); found: 1427.8021. Elemental anal. calcd. for C88 H116 F2 N4 O2 S4 : C 74.01, H 8.19, N 3.92. Found: C 73.51, H 8.20, N 3.84.
DPP-3FBVCNT (yield: 36%): 1 H NMR (500 MHz, 373.2 K, CDCl2 CDCl2 , TMS): δ = 8.78 (d, J = 4.0 Hz, 2H), 7.70 (t, J = 7.5 Hz, 2H), 7.62 (d, J = 7.5 Hz, 6H), 7.35 (d, J = 3.5 Hz, 2H), 7.28 (d, J = 5.0 Hz, 2H), 7.22 (s, 2H), 7.02 (t, J = 3.5 Hz, 2H), 3.98 (d, J = 7.5 Hz, 4H), 1.91 (m, 2H), 1.32–1.16 (m, 80H), 0.78–0.77 (m, 12H, -CH3 ). 13 C NMR (126 MHz, 373.2 K, CDCl2 CDCl2 , TMS): δ = 161.72, 160.16, 158.15, 141.24, 139.97, 138.94, 136.77, 135.71, 135.13, 131.05,
128.82, 128.32, 128.19, 127.90, 127.18, 125.50, 116.78, 116.59, 116.26, 109.49, 108.05,
46.83, 38.21, 31.85, 30.00, 29.60, 29.56, 29.47, 29.21, 26.56, 22.54, 13.88. 19 F NMR (470 MHz, 373.2 K, CDCl2 CDCl2 , TMS): δ = −130.17. HRMS (MALDI): calcd. for C88 H117 F2 N4 O2 S4 [M + H]+ (1427.8022); found: 1427.8013. Elemental anal. calcd. for C88 H116 F2 N4 O2 S4 : C 74.01, H 8.19, N 3.92. Found: C 73.59, H 8.30, N 3.74.
